Rotary kiln for continuous heating of material without contact with heating gases

ABSTRACT

A rotary kiln for the continuous carbonization of coal is formed of a longitudinally extending inner shell surrounded by a longitudinally extending outer shell so that heating-gas passages extending the longitudinal direction of the kiln about the inner shell. Within the inner shell, intermediate the charging end and discharging end of the kiln, a cavity or pool is provided for holding the coal in a liquid state for a required period of time during its travel through the kiln. At the discharge end the inner shell extends longitudinally beyond the outer shell and a stationary firing chamber is provided at the end of the outer shell so that it is spaced from the discharge end. At the charging end of the kiln, a fixed chimney hood is arranged in communication with the heating-gas passages about the inner shell. By sealing the interior of the inner shell from the heating-gas passages and also from the atmosphere, the coal can be continuously carbonized without being contacted by the heating-gas or the atmosphere.

United States Patent [72] inventor Madhusudan Raghunath Ternbe c/o Tembe Industries Tembes Bungalow,

Sykes Extension P.0. Shakapurl, Kolhapur,

India [21] Appl. No. 861,876 [22] Filed Sept. 29, 1969 [45] Patented Nov. 9, 1971 [32] Priority Nov. 28, 1968 [33] Great Britain [31] 56,566/68 [54] ROTARY KILN FOR CONTINUOUS HEATING OF MATERIAL WITHOUT CONTACT WITH HEATING Primary Examiner-John J. Camby Attorney-McGlew and Toren ABSTRACT: A rotary kiln for the continuous carbonization of coal is formed of a longitudinally extending inner shell surrounded by a longitudinally extending outer shell so that heating-gas passages extending the longitudinal direction of the kiln about the inner shell. Within the inner shell, intermediate the charging end and discharging end of the kiln, a cavity or pool is provided for holding the coal in a liquid state for a required period of time during its travel through the kiln. At the discharge end the inner shell extends longitudinally beyond the outer shell and a stationary firing chamber is provided at the end of the outer shell so that it is spaced from the discharge end. At the charging end of the kiln, a fixed chimney hood is arranged in communication with the heating-gas passages about the inner shell. By sealing the interior of the inner shell from the heating-gas passages and also from the atmosphere, the coal can be continuously carbonized without being contacted by the heating-gas or the atmosphere.

PATENTEUHUV 9 mi 8 SHEET 2 OF 2 I nvenlor HHDHU$U RN RHbHUNHTH TE HBE WW A Homeyj ROTARY KILN FOR CONTINUOUS HEATING OF MATERIAL WITHOUT CONTACT WITH HEATING GASES This invention relates to a rotary kiln for continuous carbonization of coal without contact with heating gases and the atmosphere.

The existing type of rotary kiln generally consists of a long inclinably disposed cylindrical steel shell lined with refractory material. The material to be heated is continuously charged in the rotating shell from the elevated end while thefuel is burnt at the discharge end and the flames and hot gases travel along the length of the shell and are discharged at the material charging end. Thus the material comes in direct contact with the flames and gases.

The existing method of. carbonization of coal essentially consists of a batch-type heating process. A batch of coal is charged in an oven or in a retort. Ovens are heated indirectly by burning gases in adjacent chambers while retorts are externally heated. These ovens or retorts are sealed to prevent ingress of air, and outlets are provided for collection .of volatile gases which are given off by coal. After the volatile matter is given off and the desired final temperature of coke is reached, the mass of coke in the oven is removed.

The object of the present invention is to have a continuous process for carbonization of coal, removal of volatile matter and manufacture of coal.

It is known that coal changes its phase during heating e.g. coal is solid up to a temperature of about 350 C. and becomes plastic between temperature range of 350-450 C. During this period a major portion of volatile matter is driven out. The coal again becomes solid after 450? C. and forms coke.

The object of this invention is therefore also to so construct the Kiln that heating is effected without coming into contact with heating gases and soakingtime during an intermediate temperature range in the continuous heating process of the material is possible. The term soaking time means that the material is held in the desired temperature zone for the required period of time.

According to this invention the rotary kiln for continuous carbonization of coal, without contact with heating gases and atmosphere, comprises an inner shell and an outer shell, passages formed between the inner shell and outer shell for the flow of heating gases wherein at the discharge end of the kiln the inner shell extends beyond the outer shell, a stationary disc having a charging pipe at'the charging end of the kiln, a cavity or pool formed in the kiln to allow soaking time for the coal during its travel through the kiln, a stationary firing chamber around the extended inner shell and installed before the discharge end of the kiln, burners one for each passage located in the firing chamber for allowing entry of air to the firing chamber, a fixed chimney hood surrounding the kiln near the charging end of the kiln, the hood communicating with the passages between the inner shell and the outer shell, a discharge chamber at the outlet end, sealing means being provided between the fixed firing chamber and the kiln shells, between the discharge chamber and the inner shell and between the chimney hood and the outer shell-respectively so that during carbonization the coal in the kiln does not come in contact with the outside atmosphere and the coal is heated indirectly throughout its travel within the inner shell of the kiln without coming in contact with the heating gases.

The invention will now be more fully described with reference to the accompanying drawings, in which:

FIG. 1 shows the kiln in section; FIG. 2 shows the section of the kiln along line X-X in FIG.

FIGS. 3, 3A and 3B show a part of the kiln in section illustrating different embodiments of forming a pool, and

FIG. 4 shows a section along line 2-2 in FIG. 1.

Referring to the drawings, A shows the outer shell lined with refractory material B. D is the inner shell which carries the coal E to be heated. The two shells A and D are spaced from each other by radial supports of refractory material to form a series of longitudinal passages C which can be straight or helical extending along the length of the outer shell. I

The hot gases are fed through burners F located within a fixed firing chamber G having an air inlet H and a gas fuel pipe I. The flames from the burners, one for each passage, and the hot gases flow through the passages C from the discharge to the charging end of the kiln.

At the charging end, the coal is fed through a hopper J with a double bell. arrangement J, and a feeder such as a screw J, and inlet pipe 1,. The pipe J, passes through a fixed disc K fitted at the charging end through seals S to'prevent escape of gases. Volatile matter formed during the heating of the coal is collected through a pipe I... At the charging end is fitted a chimney hood M through seals S which hood communicates with passages C through openings M, in the outer shell A. At the discharge end the outer shell A is stepped at A, so that the inner shell is longer than the outer shell where the fixed firing chamber sealed at S is installed. The coke is discharged into a discharge chamber N having an inlet 0 for introducing any gas under pressure. The chamber N has double-bell arrangement P asillustrated. The kiln is provided with a cavity 0 to allow for soaking time. This cavity may be formed either by gradually reducing the diameter of the inner shell D (FIG. 3B) or by enlarging the diameter of the inner shell (FIG. 3) or by forming a venturi (FIG. 3A).

Coal evolves maximum gases during the critical range of 350450 C. The invention proposes to allow coal to remain in this temperature zone for sufficient time so as to complete the process. It is also possible to soak the coke at the end temperature of l,000 C. by adjustment of diameters of the kiln. The chimney M may be in the shape of a volute as shown in FIG. 4.

The kiln is inclinably disposed and is mounted on rollers R in the conventional manner.

The kiln is intended for carbonization of coal, so that crushed coal can be heated without contact with heating gases and atmospheric and in a continuous operation.

The final temperature is generally about 1,000? C. to l,l00 C., in-case of high-temperature carbonization, and 750-850 C. in case of low-temperature carbonization. Whencoal is heated without contact with air,'it first becomes plastic or semiliquid between critical temperature range of about 350450 C. It can now remain in the cavity Q for the required duration. During heating volatile matter in the coal is given off and the coke that remains behind forms hard'or soft coke depending upon the nature of coal and final temperature of carbonization. In the cavity due to surface tension and rotating action of the kiln, uniform spheres or globules are formed.

The coal will be made to traverse along the length of the kiln, while it is being heated by the heating gases flowing through the longitudinal passages shown. Thus a perfect countercurrent heating will be attained.

The advantages of the coking kiln of this invention for carbonizationof coal can be summarized as follows:

a. The "Coking Kiln will not require costly brick work and regenerators.

b. The various machines e.g. charging lorry, coke pusher, coke guide, quenching car required by the present coking batteries will not be required;

c. Coke will be formed in globules of substantially uniform size which can be controlled by varying the speed of rotation and the rate of coal feed;

d. Coal gas will be always drawn to regions of lower temperature so that valuable hydrocarbons will not be destroyed;

e. Highly swell coals can be easily handled.

Having this described and ascertained the subject matter of the invention what I claim is:

l. A rotary kiln for the continuous carbonization of coal without any contact between the coal and the heating gases and the atmosphere, the rotary kiln having a discharge end and a charging end, comprising a longitudinally extending inner shell and a longitudinally extending outer shell enclosing the inner shell and arranged for forming passages therebetween for the flow of heating gases, said inner shell extending longitudinally beyond said outer shell at the discharge end of the kiln, a stationary disc extending across the end of said inner shell at the charging end of the kiln, a charging pipe extending through said stationary disc into said inner shell for charging coal into said inner shell, said inner shell being shaped intermediate its charging and discharge ends for forming a cavity extending around the inner shell in the direction transverse to its longitudinal direction for providing a space for collecting coal during its travel through the kiln to allow soaking time for the coal, means forming a stationary firing chamber around the portion of said inner shell extending longitudinally from said outer shell adjacent the discharge end of the kiln, a burner located within said firing chamber for each passage located between said inner and outer shell, said firing chamber having an inlet thereto for admitting air into said firing chamber, a fixed chimney hood surrounding the kiln adjacent the changing end thereof, said chimney hood communicating with the passages between said inner shell and outer shell, a discharge chamber located at the discharge end of the kiln in communication with said inner shell, sealing means being provided between said fixed firing chamber and said inner and outer shells, between said discharge chamber and said inner shell and between said chimney hood and said outer shell respectively so that during carbonization within the inner shell of the kiln the coal does not come in contact with the outside atmosphere and it is heated indirectly throughout its travel through the inner shell without coming in contact with the heating gases.

2. A rotary kiln, as set forth in claim 1, characterized in that said discharge chamber has an inlet for introducing gas under pressure into said inner shell.

3. A rotary kiln, as set forth in claim 1, characterized in that means being provided within said charging pipe and said discharge chamber for preventing the passage of atmospheric air into said inner shell. 

1. A rotary kiln for the continuous carbonization of coal without any contact between the coal and the heating gases and the atmosphere, the rotary kiln having a discharge end and a charging end, comprising a longitudinally extending inner shell and a longitudinally extending outer shell enclosing the inner shell and arranged for forming passages therebetween for the flow of heating gases, said inner shell extending longitudinally beyond said outer shell at the discharge end of the kiln, a stationary disc extending across the end of said inner shell at the charging end of the kiln, a charging pipe extending through said stationary disc into said inner shell for charging coal into said inner shell, said inner shell being shaped intermediate its charging and discharge ends for forming a cavity extending around the inner shell in the direction transverse to its longitudinal direction for providing a space for collecting coal during its travel through the kiln to allow soaking time for the coal, means forming a stationary firing chamber around the portion of said inner shell extending longitudinally from said outer shell adjacent the discharge end of the kiln, a burner located within said firing chamber for each passage located between said inner and outer shell, said firing chamber having an inlet thereto for admitting air into said firing chamber, a fixed chimney hood surrounding the kiln adjacent the changing end thereof, said chimney hood communicating with the passages between said inner shell and outer shell, a discharge chamber located at the discharge end of the kiln in communication with said inner shell, sealing means being provided between said fixed firing chamber and said inner and outer shells, between said discharge chamber and said inner shell and between said chimney hood and said outer shell respectively so that during carbonization within the inner shell of the kiln the coal does not come in contact with the outside atmosphere and it is heated indirectly throughout its travel through the inner shell without coming in contact with the heating gases.
 2. A rotary kiln, as set forth in claim 1, characterized in that said discharge chamber has an inlet for introducing gas under pressure into said inner shell.
 3. A rotary kiln, as set forth in claim 1, characterized in that mEans being provided within said charging pipe and said discharge chamber for preventing the passage of atmospheric air into said inner shell. 